- Synthesis of 3-substituted 8-hydroxy-3,4-dihydroisocoumarins via successive lateral and ortho-lithiations of 4,4-dimethyl-2-(o-tolyl)oxazoline
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Sequential treatment of 4,4-dimethyl-2-(o-tolyl)oxazoline in THF with sec-BuLi, aromatic or aliphatic aldehydes, sec-BuLi, B(OMe)3, and H2O2 produced the laterally alkylated and ortho-hydroxylated oxazolines in one-pot. Treatment of these products with TFA in aqueous THF provided 3-substituted 8-hydroxy-3,4-dihydroisocoumarins in 44-75% overall yields. This procedure allowed the short synthesis of (±)-hydrangenol and (±)-phyllodulcin, naturally occurring 3,4-dihydroisocoumarins of pharmacological interest. A more economical synthesis of (±)-phyllodulcin via the trianion intermediate is also described.
- Tahara, Naruki,Fukuda, Tsutomu,Iwao, Masatomo
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- Annelation reactions of enaminones with ethyl acetoacetate. Studies on the β-carbonyl compounds connected with β-polyketides. XI
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Though condensation at either the carbonyl oxygen or the unsaturated carbon adjacent to nitrogen of enaminones can occur in the reaction with the active methylene of ethyl acetoacetate, the results obtained in the condensation reactions of the enaminones
- Takeuchi,Handa,Koyama,Kamata,Goto,Tobinaga
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p. 1655 - 1658
(2007/10/02)
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- Biogenetic-type Synthesis of 3,4-Dihydro-8-hydroxy-3-phenylisocoumarin (Studies on the β-Carbonyl Compounds connected with the β-Polyketides. V)
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A biogenetic-type synthesis of a dihydroisocoumarin, 3,4-dihydro-8-hydroxy-3-phenylisocoumarin (1), from trans-cinnamaldehyde (13) modelled on the polyketide mode of biosynthesis is described.Keywords - β-polyketides; biogenetic-type synthesis; condensati
- Takeuchi, Naoki,Tobinaga, Seisho
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p. 3007 - 3012
(2007/10/02)
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